The present invention generally relates to an apparatus for protecting the catalyst particles of proton exchange membrane (PEM) fuel cells from poisoning by carbon monoxide, a fuel cell utilizing the apparatus, and a method for manufacturing the apparatus.
Fuel cells use the chemical energy produced in the reaction between hydrogen and oxygen to generate electricity that does not require combustion of fossil fuels and is clean. In a basic configuration of a fuel cell, hydrogen gas flows to the anode on one side of the fuel cell, while air flows to the cathode on the other side of the fuel cell. A platinum catalyst deposited on the anode splits the hydrogen molecule into two positive hydrogen ions (protons) and two negatively charged electrons. A proton exchange membrane (PEM) positioned between the anode and the cathode allows only the positively charged hydrogen protons to pass through it and reach the cathode. The negatively charged electrons travel along an external electrical circuit to the cathode, creating an electrical current. At the cathode, the negatively charged electrons and positively charged hydrogen ions combine with the oxygen typically from an air feed to form water which flows out of the cell.
The platinum catalyst of a fuel cell is susceptible to trace amounts of poisons, most notably carbon monoxide, which are generally present in hydrogen gas manufactured from the reforming of hydrocarbons. Catalyst poisons, such as carbon monoxide bind with the platinum thereby poisoning the electrode and decreasing fuel cell performance over time. Even trace amounts of carbon monoxide as low as 10 ppm can have a detrimental effect on the shelf life of the expensive platinum catalyst.
As can be seen, there is a need for a solution to reduce or eliminate the poisoning of platinum catalysts used for splitting the hydrogen molecule by carbon monoxide.